We've done it both ways. IMO, it really depends more on how you eat, what your budget is, how much time you want to spend doing things in the park... and how fond you are of cooking on vacation?
We don't do the
DDP anymore - partly because we felt like we were spending an awful lot of time planning for meals and planning around meals, and partly because they changed the plan (to no longer include appetizer and gratuity) and it didn't make as much sense for us economically any more.
But the 2 years we did it we enjoyed it very much. We consider dining a big part of our vacation, and the DDP allowed us to try a lot of restaurants on property that we never would have otherwise because of the out-of-pocket costs.
Keep in mind that doing a TS meal every day will take up a good chunk of time, and will require planning to make sure you get all your ADRs lined up. Also take into account how much food you'd normally eat in a given day, and how much you're going to be getting on the DDP. Both times we did it (2006 & 2007)we found ourselves with lots of desserts in the camper fridge and a whole stack of CS credits left at the end of our stay (which we "bought" all our friends lunch one day!)
If you're looking at it from a budget standpoint, I'd recommend checking out the actual
menus and pricing out what a typical day would cost you eating the way your normally would vs the cost of the meal plan (don't forget to add in the gratuity).